Advice on DOD 280 comp.

[oldrocker]

I'm still debugging the DOD 280 from Tonepad.  I made a LED/LDR in shrink wrap and thought that was the problem so I ordered a VTL5C2 from Newark and they sent me a VTL5C3 so I hope that works.  I'm using .047 caps instead of the .05 caps.  IC1 is a TL082. 

Q1 C- 8.25 Volts
     B- 0 Volts
     E- Grounded

Q2 C- 8.25 Volts
     B- 0 Volts
     E- Grounded

IC Pin 1- 4.72 volts
    Pin 2- 4.72 volts
    Pin 3- 4.49 volts
    Pin 4- Grounded
    Pin 5- 4.7 volts
    Pin 6- 4.71 volts
    Pin 7- 4.71 volts
    Pin 8- 9.44 volts

After any .047 cap there's no voltage. 
P.S. I didn't add the Millennium mods.

[oldrocker]

OK.  I replaced the TL082 IC with a 358.  I also had 4401 trannys in there and replaced them with 3904's.  My question now is how transparent is this effect?  Since I switched the LED/ LDR with an actual VCT5C3 how can I tell if the LED is lighting.  With my shrink tube LED/LDR I could see through the back and I could see the LED wasn't lighting up.  But this Vactrol is fully enclosed so I'm not sure if it's working.  I'm not hearing squashed type compression like I can with the Orange Squeezer when I drive the input hard.  When I did a search in this forum it sounds like I should be able to tell without a doubt.  I'd like to hear from anyone else who built this pedal.  Did U like it?  I read a lot of people thought the compression was too much.  If that's the case I assume mine still isn't working right.

[R.G.]

There's nothing obvious in the DC voltages.

Are you sure the LED is installed the right way round?

You can test the LED/LDR module by using a 9V battery and a 1K resistor on the LED end while your ohmmeter is clamped to the LDR. No connection, big resistance; connection, resistance under 10K. If it does that, the LED/LDR is working, and the + battery side is connected to the anode.

Once you've sorted that out, leave your voltmeter on the collectors of the two transistors. When you hit a big chord, that point should sink from its nearly-9V level to some lower voltage.

[oldrocker]

OK.  I did clamp on to the collector and read the voltage as I hit a loud chord.  The voltage does come down depending on how hard I strum.  The collector voltage comes down and the Base voltage comes up about the same amount.  I'm getting a distortion when playing.  Is this normal?  I seems like it's working I guess but the sizzle is disturbing.

[oldrocker]

Well I made the 280A mods from the GGG website.  That only consisted of replacing the 1M resister that straddled the LDR with a 3M and adding a 10uf cap from +9 volts to ground.  It is working with no doubt.  When I plugged my MP3 player into it the volume knob stops from about mid to full and the 280 won't let the loudness increase.  Still a little sizzle but it's not too bad.  Thanks R.G. as always you were a great help.

[oldrocker]

I removed the VTL5C3 and added my shrink tube LED/LDR back into the 280 and now it's compressing better.  For some reason the VTL5C3 just wasn't strong enough.  Now I can hear the squashed compression I was expecting.  After I knew the Vactrol was working I wanted to see if I could see the LED coming on with the homemade LED/LDR.  I saw the LED working this time and when I plugged in and started playing it was compressing like mad.  After the chord fades you can hear the feedback from the amp kick in.  I don't know if a VTL5C2 would work any different.  That's what I ordered and Newark sent me the wrong one.  Although in past threads I read they both should work.